Dual fuel injector and engine using same

Abstract

A dual fuel injector may be used to inject both gas and liquid fuel into a cylinder of a compression ignition engine. An injector body defines a first set of nozzle outlets, a second set of nozzle outlets, a first fuel inlet and a second fuel inlet. A dual solenoid actuator includes a first armature, a first coil, a second armature and a second coil that share a common centerline. The dual solenoid actuator has a non-injection configuration at which the first armature is at an un-energized position and the second armature is at an un-energized position. The dual solenoid actuator has a first fuel injection configuration at which the first fuel inlet is fluidly connected to the first set of nozzle outlets, the first armature is at an energized position and the second armature is at the un-energized position.

What is claimed is: 
     
       1. An engine comprising:
 an engine housing defining a plurality of cylinders; 
 a dual fuel system including a plurality of fuel injectors, each including an injector body defining a first set of nozzle outlets and a second set of nozzle outlets positioned for direct injection into one of the plurality of cylinders; 
 the dual fuel system including a first fuel common rail fluidly connected to a first fuel inlet of each of the plurality of fuel injectors, and a second fuel common rail fluidly connected to a second fuel inlet of each of the plurality of fuel injectors; 
 each of the plurality of fuel injectors including a dual solenoid actuator that includes a first armature, a first coil, a second armature and a second coil that share a common centerline with respective first and second pushers coupled to the first armature and the second armature; 
 the respective first and second pushers being configured to control a first control valve member and a second control valve member, respectively, corresponding to first and second needle valve members; and 
 the first and second needle valve members being further controlled by a shared spring configured to open or close a first pressure relief passage and a second pressure relief passage via the first and second pushers. 
 
     
     
       2. The engine of  claim 1 , wherein the dual fuel system includes a plurality of outer tubes, each extending into the engine housing between a quill and one of the plurality of fuel injectors, and
 wherein the dual fuel system includes a plurality of inner tubes, each extending into the engine housing through one of the plurality of outer tubes and being compressed between a conical seat on the quill and a conical seat on one of the plurality of fuel injectors. 
 
     
     
       3. The engine of  claim 1 , wherein the first fuel common rail is fluidly connected to a source of liquefied natural gas and the second fuel common rail is fluidly connected to a source of liquid compression ignition fuel. 
     
     
       4. The engine of  claim 1 , wherein the first needle valve member is movable in the injector body between an open position and a closed position along the common centerline, and the second needle valve member is movable in the injector body between an open position and a closed position along a different centerline that is parallel to, but offset from, the common centerline. 
     
     
       5. The engine of  claim 1 , wherein the first needle valve member includes a closing hydraulic surface exposed to a fluid pressure in a first control chamber, and the second needle valve member includes a closing hydraulic surface exposed to a fluid pressure in a second control chamber, and each of the first control chamber and the second control chamber are fluidly connected to the first fuel inlet. 
     
     
       6. The engine of  claim 1 , wherein the dual solenoid actuator has a non-injection configuration at which the first armature is at an un-energized position and the second armature is at an un-energized position,
 the dual solenoid actuator has a first fuel injection configuration at which the first fuel inlet is fluidly connected to the first set of nozzle outlets, the first armature is at an energized position and the second armature is at the un-energized position, 
 the dual solenoid actuator has a second fuel injection configuration at which the second fuel inlet is fluidly connected to the second set of nozzle outlets, the first armature is at the un-energized position and the second armature is at an energized position, and 
 the dual solenoid actuator has a combined fuel injection configuration at which the first set of nozzle outlets is fluidly connected to the first fuel inlet, the second fuel inlet is fluidly connected to the second set of nozzle outlets, the first armature is at the energized position and the second armature is at an energized position. 
 
     
     
       7. The engine of  claim 1 , wherein the first control valve member is operably coupled to move into and out of contact with a first valve seat responsive to movement of the first armature between an un-energized position and an energized position, respectively, and
 wherein the second control valve member is operably coupled to move into and out of contact with a second valve seat responsive to movement of the second armature between an un-energized position and an energized position, respectively. 
 
     
     
       8. An engine comprising:
 an engine housing defining a plurality of cylinders; 
 a dual fuel system including a plurality of fuel injectors, each including an injector body defining a first set of nozzle outlets and a second set of nozzle outlets positioned for direct injection into one of the plurality of cylinders; 
 the dual fuel system including a first fuel common rail fluidly connected to a first fuel inlet of each of the plurality of fuel injectors, and a second fuel common rail fluidly connected to a second fuel inlet of each of the plurality of fuel injectors; 
 each of the plurality of fuel injectors including a dual solenoid actuator that includes a first armature, a first coil, a second armature and a second coil that share a common centerline and further includes a shared stator upon which the first coil and the second coil are mounted, the first armature and the second armature being coupled to a first pusher and a second pusher, respectively, the first pusher and the second pusher being operatively coupled to a first control valve member and a second control valve member, respectively, via a first valve seat and a second valve seat, respectively; and 
 said dual solenoid actuator being operatively coupled to a first needle valve member and a second needle valve member in the injector body, the first needle valve member and the second needle valve member movable upon movement of the first valve seat and second valve seat, respectively, by a corresponding movement of a shared spring to open or close a first pressure relief passage and a second pressure relief passage via the first pusher and the second pusher, respectively, and wherein the opening and closing of the first pressure relief passage and the second pressure relief passage opens and closes a first hydraulic surface of the first needle valve member and a second hydraulic surface of the second needle valve member. 
 
     
     
       9. The engine of  claim 8 , wherein the dual fuel system includes a plurality of outer tubes, each extending into the engine housing between a quill and one of the plurality of fuel injectors, and
 wherein the dual fuel system includes a plurality of inner tubes, each extending into the engine housing through one of the plurality of outer tubes and being compressed between a conical seat on the quill and a conical seat on one of the plurality of fuel injectors. 
 
     
     
       10. The engine of  claim 8 , wherein the first fuel common rail is fluidly connected to a source of liquefied natural gas and the second fuel common rail is fluidly connected to a source of liquid compression ignition fuel. 
     
     
       11. The engine of  claim 8 , wherein the first needle valve member is movable in the injector body between an open position and a closed position along the common centerline, and the second needle valve member is movable in the injector body between an open position and a closed position along a different centerline that is parallel to, but offset from, the common centerline. 
     
     
       12. The engine of  claim 8 , wherein the first needle valve member includes a closing hydraulic surface exposed to a fluid pressure in a first control chamber, and the second needle valve member includes a closing hydraulic surface exposed to a fluid pressure in a second control chamber, and each of the first control chamber and the second control chamber are fluidly connected to the first fuel inlet. 
     
     
       13. The engine of  claim 8 , wherein the dual solenoid actuator has a non-injection configuration at which the first armature is at an un-energized position and the second armature is at an un-energized position,
 the dual solenoid actuator has a first fuel injection configuration at which the first fuel inlet is fluidly connected to the first set of nozzle outlets, the first armature is at an energized position and the second armature is at the un-energized position, 
 the dual solenoid actuator has a second fuel injection configuration at which the second fuel inlet is fluidly connected to the second set of nozzle outlets, the first armature is at the un-energized position and the second armature is at an energized position, and 
 the dual solenoid actuator has a combined fuel injection configuration at which the first set of nozzle outlets is fluidly connected to the first fuel inlet, the second fuel inlet is fluidly connected to the second set of nozzle outlets, the first armature is at the energized position and the second armature is at the energized position.